The Human Research Facility (HRF) Continuous Blood Pressure Device (CBPD) is a noninvasive measurement device that measures blood pressure continually at the finger using plethysmography (which measures the change in volume of the finger due to blood flow). Finger cuffs, which have a small bladder and an infrared spectral measurement transmitter and receiver, are placed around the fingers. Finger cuffs are provided in three different sizes to accommodate all ISS crewmembers. A basic three-lead electrocardiogram (ECG) amplifier is also provided for measurement of ECG data from the subject.

The CBPD is configured in a waist belt with three pouches to allow for individual (but electrically connected) stowage of the pump, microprocessor, and direct-current power adapter. The waist-pouch configuration supports the front-end servo-controller, which operates attached to the back of the forearm and interfaces to the microprocessor and pump through electrical and air tube connections. The front end controls the pressure and data interface to the finger cuffs being used for arterial blood pressure monitoring. The front-end unit sends pressure feedback from infrared light-emitting diodes (LEDs) to the microprocessor for pump control and data acquisition purposes. The microprocessor has an internal flash memory card that can store up to 40 MB of blood pressure and heart rate data. The CBPD power and data interfaces reside in the microprocessor unit.

When in use, the CBPD is powered by connecting to a 28Vdc power source and can, via software, interface to the HRF PC or HRF Pulmonary Function Module/Photoacoustic Analyzer Module (PFM/PAM; part of the Pulmonary Function System or PFS) to download, display, and archive data using a RS-232 connection. Additional data interfaces include input for analog ECG, heart rate, and respiration timing and output for analog blood pressure, ECG, and height correction. The hardware (excluding the frontend unit which goes on the forearm) can be worn around the crewmembers' waist or it can be attached to a handrail or other HRF hardware depending on the application. Prior to start of data collection, the user sets the appropriate software parameters including age, weight, height, etc. This can be done via the frontend unit keypad/display or, if using the PC, via the software interface to the CBPD.

The CBPD is powered by connecting to the 28Vdc power outlet on the HRF Rack. Data can be sent real-time to the HRF-PC or the PFS via RS-232. Alternatively, it can be stored on internal memory for later downlink.

The HRF CBPD was used for CSA’s CCISS experiment and is currently used by CSA’s BP Reg experiment.